The present invention relates generally to shaft couplings and more particularly to a shaft coupling for transmitting a torque force from one shaft to another.
The problem of how to couple one shaft to another for transmitting a torque force is a longstanding one. This has particularly been true in the farming community because the power take-off of an agricultural tractor frequently needs to be connected and disconnected to utilize one implement and then another. This problem has been solved in the past in one degree or another, and one of the most commercially successful of these solutions is a connection of the type disclosed in U.S. Pat. No. 2,448,278, which was patented in 1948.
In U.S. Pat. No. 2,448,278, a pin is spring biased to one position within a coupling housing such that it will contact and hold one spline of a power take-off to thereby hold the coupling together. In another position of the pin, it is moved so that it does not block or contact any of the splines and thereby allows the housing to be removed from the power take-off shaft.
Since the time that the coupling disclosed in U.S. Pat. No. 2,448,278 was developed, the horse-power rating of typical agricultural tractors has continued to increase . Because of the very high torque which can be developed from the power take-offs of modern day agricultural tractors, it is desirable that the coupling be held at more than one point and on more than one spline of the power take-off shaft. A French Pat. No. 1,102,886 patented in 1955, discloses a design for locking on all of the splines of a power take-off shaft, but this design has not become a commercial success, at least not in this country, presumably because of its somewhat complicated structure utilized to position and bias the locking splines.